Some education if someone has the time, please

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Dana

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And once hung on the nose of an E-AB aircraft, you are free to maintain, modify or overhaul that formerly certified aircraft engine to your hearts content. As the manufacturer, you determine the timeframe and the inspection criteria for overhaul.
I've wondered about that. If you have the reduced (25 vs. 40 hours) phase 1 test time because you used a certificated engine/propeller combination, are you then obligated to follow all manufacturer's guidelines and ADs to maintain that engine's certificated status?

When I bought my plane, the Lycoming data plate for the engine in my plane... was in an envelope with the logbooks.
 

proppastie

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Depending on the engine at tbo you probably get 500 to 1000 more hours. A65 is bullet-proof

Might want to learn to fly first though. Outlook might change.
 

TFF

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The engine companies want the tags removed, the FAA wishes the tags on for data if crashed. It voids the certification once on a homebuilt until a conformity inspection is done by an A&P and written in the logs. A friend with his first RV found a used certified Lycoming and it required 25 hrs to fly off. The second one he built and splurged for a new Lycoming but it was the one Vans specs out, 40 hr fly off because it was not a certified engine by the data tag. Once on a homebuilt, you can do anything you want and fly it for as long as you want. There is no required TBO. Only essentially certificated operations like airlines have to follow TBOs; only a few exceptions.
 

Toobuilder

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I've wondered about that. If you have the reduced (25 vs. 40 hours) phase 1 test time because you used a certificated engine/propeller combination, are you then obligated to follow all manufacturer's guidelines and ADs to maintain that engine's certificated status?
Nope. The 25 hour thing is an option at the time of initial AWC. There is generally no requirement to maintain that initial configuration beyond the initial inspection.
 

geosnooker2000

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https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_43-12A_CHG_1.pdf

Which if you read points out a couple of relevant points in the FARs.

FAR 43.3 g

(g) Except for holders of a sport pilot certificate, the holder of a pilot certificate issued under part 61 may perform preventive maintenance on any aircraft owned or operated by that pilot which is not used under part 121, 129, or 135 of this chapter. The holder of a sport pilot certificate may perform preventive maintenance on an aircraft owned or operated by that pilot and issued a special airworthiness certificate in the light-sport category.



FAR 43 appendix A Paragraph C

(c) Preventive maintenance. Preventive maintenance is limited to the following work, provided it does not involve complex assembly operations:

(1) Removal, installation, and repair of landing gear tires.

(2) Replacing elastic shock absorber cords on landing gear.

(3) Servicing landing gear shock struts by adding oil, air, or both.

(4) Servicing landing gear wheel bearings, such as cleaning and greasing.

(5) Replacing defective safety wiring or cotter keys.

(6) Lubrication not requiring disassembly other than removal of nonstructural items such as cover plates, cowlings, and fairings.

(7) Making simple fabric patches not requiring rib stitching or the removal of structural parts or control surfaces. In the case of balloons, the making of small fabric repairs to envelopes (as defined in, and in accordance with, the balloon manufacturers' instructions) not requiring load tape repair or replacement.

(8) Replenishing hydraulic fluid in the hydraulic reservoir.

(9) Refinishing decorative coating of fuselage, balloon baskets, wings tail group surfaces (excluding balanced control surfaces), fairings, cowlings, landing gear, cabin, or cockpit interior when removal or disassembly of any primary structure or operating system is not required.

(10) Applying preservative or protective material to components where no disassembly of any primary structure or operating system is involved and where such coating is not prohibited or is not contrary to good practices.

(11) Repairing upholstery and decorative furnishings of the cabin, cockpit, or balloon basket interior when the repairing does not require disassembly of any primary structure or operating system or interfere with an operating system or affect the primary structure of the aircraft.

(12) Making small simple repairs to fairings, nonstructural cover plates, cowlings, and small patches and reinforcements not changing the contour so as to interfere with proper air flow.

(13) Replacing side windows where that work does not interfere with the structure or any operating system such as controls, electrical equipment, etc.

(14) Replacing safety belts.

(15) Replacing seats or seat parts with replacement parts approved for the aircraft, not involving disassembly of any primary structure or operating system.

(16) Trouble shooting and repairing broken circuits in landing light wiring circuits.

(17) Replacing bulbs, reflectors, and lenses of position and landing lights.

(18) Replacing wheels and skis where no weight and balance computation is involved.

(19) Replacing any cowling not requiring removal of the propeller or disconnection of flight controls.

(20) Replacing or cleaning spark plugs and setting of spark plug gap clearance.

(21) Replacing any hose connection except hydraulic connections.

(22) Replacing prefabricated fuel lines.

(23) Cleaning or replacing fuel and oil strainers or filter elements.

(24) Replacing and servicing batteries.

(25) Cleaning of balloon burner pilot and main nozzles in accordance with the balloon manufacturer's instructions.

(26) Replacement or adjustment of nonstructural standard fasteners incidental to operations.

(27) The interchange of balloon baskets and burners on envelopes when the basket or burner is designated as interchangeable in the balloon type certificate data and the baskets and burners are specifically designed for quick removal and installation.

(28) The installations of anti-misfueling devices to reduce the diameter of fuel tank filler openings provided the specific device has been made a part of the aircraft type certificiate data by the aircraft manufacturer, the aircraft manufacturer has provided FAA-approved instructions for installation of the specific device, and installation does not involve the disassembly of the existing tank filler opening.

(29) Removing, checking, and replacing magnetic chip detectors.

(30) The inspection and maintenance tasks prescribed and specifically identified as preventive maintenance in a primary category aircraft type certificate or supplemental type certificate holder's approved special inspection and preventive maintenance program when accomplished on a primary category aircraft provided:
(i) They are performed by the holder of at least a private pilot certificate issued under part 61 who is the registered owner (including co-owners) of the affected aircraft and who holds a certificate of competency for the affected aircraft (1) issued by a school approved under §147.21(e) of this chapter; (2) issued by the holder of the production certificate for that primary category aircraft that has a special training program approved under §21.24 of this subchapter; or (3) issued by another entity that has a course approved by the Administrator; and

(ii) The inspections and maintenance tasks are performed in accordance with instructions contained by the special inspection and preventive maintenance program approved as part of the aircraft's type design or supplemental type design.

(31) Removing and replacing self-contained, front instrument panel-mounted navigation and communication devices that employ tray-mounted connectors that connect the unit when the unit is installed into the instrument panel, (excluding automatic flight control systems, transponders, and microwave frequency distance measuring equipment (DME)). The approved unit must be designed to be readily and repeatedly removed and replaced, and pertinent instructions must be provided. Prior to the unit's intended use, and operational check must be performed in accordance with the applicable sections of part 91 of this chapter.



------------------------------------------------------------------------------------------------------

You can still do anything more complex than that provided its done under the supervision of an appropriately rated mechanic.
Thank you for the information! This is why I came here.
 

geosnooker2000

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My business for the last 24 years has been designing, manufacturing, selling and supporting aircraft EFI systems. We've sold nearly 900 of these for auto conversions in aircraft worldwide and another 1100 for aviation engines like Lycoming, Continental, Rotax and Jabiru.

I've helped many of my customers solve a multitude of issues with both types of engines. Having been down the auto conversion route twice myself with 4 and 6 cylinder Subarus and helping all these folks, I can say that you need a serious background in engines, welding, machining and fabrication to have a hope of pulling this off successfully. Even then, many have failed and gone back to a traditional aircraft engine after years of frustration and failures. This is much harder to do than it looks at first glance.

Most who've been successful, have been engineers, machinists and mechanics. If you're not one of those, I can almost 100% assure you that you won't be able to make this work reliably and safely in any reasonable time span.

Build a plane so you can work on it yourself if that's your goal but don't attempt to roll your own auto conversion. Just trying to save you time, money and grief, based on my experiences.
Okay... Give me an example of something that I would have to MACHINE. Not fabricate, but machine. As I said in a previous post, I have been down to the block on my daily driver (successfully, I might add), so I don't know how much of a "serious background in engines" you're talking about, but I'm not without some practical experience. Is it your position that only professional engine mechanics can put together a firewall-forward design?

And I might add... since this is my thread... that a lot of the responses I have gotten (here AND elsewhere) have revolved around "time" and "trouble" and "efficiency". Well, I'm here to learn about Subaru Auto conversions. I see that they exist, so they are possible. I may, at the end of my studies decide I would rather go the Rotax route, but I'm in a Subaru sub-forum. I would have thought that I would have found a lot more enthusiasm.
Let me point out that, to all of you talking about cost, all we hear and read in the kitplanes-type articles about auto-conversions is the cost savings. I mean, that's the whole point, right? If a piston breaks, a head cracks, a pretty valve cover gets scuffed, what is the cost difference in a Lycoming part and a Subaru part? Right? Am I wrong about that? Have I got it all wrong?

People, I am not trying to build my airplane in the next 6 months. I probably won't even start for 6 months. More like a year. I'm doing the responsible thing. I'm doing my research well before I start my project. And all I want to know here is, what are the individual items it takes besides the engine (and a PSRU) etc. to have a Subaru power my plane. I didn't come here for a bunch of "aww, you don't want to get into that, it's too complicated"

Sorry to sound so reactionary. Not directed at any one person. Just please try and be helpful, not discouraging.
 

BJC

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..
Let me point out that, to all of you talking about cost, all we hear and read in the kitplanes-type articles about auto-conversions is the cost savings. I mean, that's the whole point, right? If a piston breaks, a head cracks, a pretty valve cover gets scuffed, what is the cost difference in a Lycoming part and a Subaru part? Right? Am I wrong about that? Have I got it all wrong?
I’m not “an engine guy” but I have watched friends who thought that they were have problems with Subaru conversions. Ultimately, they each went the Lycoming route, and would have have had less time and money in the FWF package had they started with the Lycoming or a clone. When considering the cost of a failed part, one must also consider the cost of potential airframe repairs that resulted from an off-airport landing. Depending on multiple factors, that could be much more expensive than an entire engine.

None of the above is intended to disparage the Subaru or other conversion FWF packages. (And it is the entire FWF package, not just the engine.) There are many examples of successful Subaru installations. Ross has a successful installation, and can point to many others.

My suggestion is: if you want to go flying in a homebuilt, use an aircraft engine or a proven clone; it you enjoy tinkering with engines, have the skills and knowledge, or want to develop them, and want to have the advantages (to some) of an auto engine, do so.

BTW, not all the vendors have treated their customers the way that they should have.


BJC
 

Dana

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OK, an overview:

There have been few really successful auto conversions. Most of the successful ones are VW, Corvair, and Subaru, note that they already look like airplane engines (4 or 6 cylinder flat opposed). The VW is the most successful, not only because it's been around for a long time, but it's very simple and air cooled. Subaru, you have more to deal with.

Automobile and aircraft engines are designed for very different duty cycles. A car engine may reach its rated HP output intermittently and briefly during acceleration, or pulling up a long hill. An aircraft engine, OTOH, will run at full power for 5-10 minutes (takeoff and climb), then cruise at 75-80% power for hours. So cooling becomes a huge factor... I'm not familiar with Subaru conversions but cooling is the limiting factor on VW conversions, which is why they top out well under 100HP. RPM is also a factor, auto engines are designed to produce their HP at a much higher rpm than is efficient for a propeller, so you need a redrive or you take the hit on propeller efficiency.

Electronic engine controls are also another factor; in cars they're designed around a the car's duty cycle and optimized for reduced emissions (for example turning on the check engine light if the catalytic converter fails, but you won't have a cat on a plane). They often include a reduced power "limp mode" to get you home if something fails, but in an airplane that reduced power might be just enough to get you to the scene of the crash.

Car engine parts are cheaper-- often a lot cheaper-- but a BJC pointed out above you have to consider the total cost of a failure, when you can't just pull over to the side of the road and fix it, or wait for a tow truck. When I flew my half VW powered plane, I was always looking for a place to land, expecting the engine to quit at any time (it never did, completely).

So what do you have to do or make? As I said, I'm not familiar with the specifics of Subarus in airplanes, but in general, you'll probably need to:
  • Make or buy and install an output pulley for the reduction drive
  • Make or buy an exhaust system to suit the airplane
  • Install a simplified ECU, or convert to carburetor
  • If you remove the stock ECU and go carburetor, install a new ignition system
  • Make and install plugs or covers for removed sensors, etc.
  • Make an engine mount
  • Make or buy a reduction drive-- a biggie, not nearly as simple as it looks, torsional vibration is the bane of redrives, sometimes you get lucky and sometimes you don't without some serious engineering effort.
  • You may have to move (and fabricate brackets for) accessories like the alternator
  • Design and fabricate a new cooling system (radiator, hoses, etc.) to suit the aircraft installation
  • Design and fabricate the cowling and ducting to direct air around the engine, not as simple as just hanging a radiator on the front of a car
If I was looking at auto conversions for the reduced cost, a VW would be the only choice, it's the only one with the established history and knowledge base to know it'll be reliable... but it still won't be as reliable as a Continental or Lycoming, and will require more attention during its lifetime. Any of the others, including Subaru, should be contemplated only if you go into it as an experimental project, and expect to (and enjoy!) spend a lot of extra time working on it both during the build and on an ongoing basis after it's flying, working out how to solve problems (there's a big difference between mechanicing an existing design and engineering something something new). Not to say that you shouldn't do it, but do it for the right reasons and know what you're getting into.
 

blane.c

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Experimental engines are the perfect place for multiple engines. If you don't entirely trust one of them, you may as well not trust several of them. If one of them rewards your mistrust maybe the others will see you home.
 

rv6ejguy

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Okay... Give me an example of something that I would have to MACHINE. Not fabricate, but machine. As I said in a previous post, I have been down to the block on my daily driver (successfully, I might add), so I don't know how much of a "serious background in engines" you're talking about, but I'm not without some practical experience. Is it your position that only professional engine mechanics can put together a firewall-forward design?

And I might add... since this is my thread... that a lot of the responses I have gotten (here AND elsewhere) have revolved around "time" and "trouble" and "efficiency". Well, I'm here to learn about Subaru Auto conversions. I see that they exist, so they are possible. I may, at the end of my studies decide I would rather go the Rotax route, but I'm in a Subaru sub-forum. I would have thought that I would have found a lot more enthusiasm.
Let me point out that, to all of you talking about cost, all we hear and read in the kitplanes-type articles about auto-conversions is the cost savings. I mean, that's the whole point, right? If a piston breaks, a head cracks, a pretty valve cover gets scuffed, what is the cost difference in a Lycoming part and a Subaru part? Right? Am I wrong about that? Have I got it all wrong?

People, I am not trying to build my airplane in the next 6 months. I probably won't even start for 6 months. More like a year. I'm doing the responsible thing. I'm doing my research well before I start my project. And all I want to know here is, what are the individual items it takes besides the engine (and a PSRU) etc. to have a Subaru power my plane. I didn't come here for a bunch of "aww, you don't want to get into that, it's too complicated"

Sorry to sound so reactionary. Not directed at any one person. Just please try and be helpful, not discouraging.
Research is good. It can save a lot of time and heartbreak down the road before you start your project.

If you look at my RV6A project pages, you'll see plenty of parts which I had to machine. Yes, you can farm those out of course. You'll be doing a lot of welding as you can see in my engine mount page.

Yes, my position is that without a solid and extensive engine, mechanical, fabrication type background, you won't be successful in building your own auto conversion. I've seen way more fail at it than succeed, even from some MEs and experienced engine guys. There are lots of things that can and will bite you along the way.

The $ cost may be lower with an auto conversion (mine was) but the time spent will be much higher. After you complete the airframe build, will you have the gumption left to start on the engine part which is another huge task in itself?

In the end though, an EJ Subaru will be way too heavy for the Sling so if you are going to build that aircraft and do an auto conversion, you'll have to look at a lighter engine. I suggest looking at the Aeromomentum packages where a lot of the work with the fuel system and redrive is already handled for you.
 

Toobuilder

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Geo- what is your primary objective? Is it to fly or tinker?

If it looks like the membership is "negative", it is just to give you a dose of reality and perhaps test your resolve. I think most here are supportive of auto conversions as a concept but if the goal is to provide "inexpensive" power for your airplane - the odds are stacked against you. Despite manufacturers claims, there really is no cookbook based plan to hang a Subie on your airplane like there is for an established aircraft engine. There is a LOT more than simply swinging a propeller. You are on your own for fuel, cooling, torsional vibration, structure, and aerodynamics.

And considering your own admittedly modest experience, I think most of us are seeing red flags. Not because we are looking down on you, but because we see an opportunity to capture another homebuilt enthusiast and we don't want that passion to expire on a long, arduous journey like an auto conversion.

So if the primary consideration is to learn, then you have a very long road ahead. I think most of us will be supportive, but you better have your eyes wide open going in. You will not be zipping around the sky anytime soon.
 

blane.c

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Finding a airplane, polishing it, tinkering on it, finding a significant other that will live in the hanger with you and help you polish the airplane. All are rewarding accomplishments. Oh yes I forgot, flying the airplane, ahh that is the sweet spot. Then you get to polish it again. For some reason people on this forum want the added joy of building it or even designing it and then building it. The heart wants what the heart wants.
 

geosnooker2000

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OK, an overview:

There have been few really successful auto conversions. Most of the successful ones are VW, Corvair, and Subaru, note that they already look like airplane engines (4 or 6 cylinder flat opposed). The VW is the most successful, not only because it's been around for a long time, but it's very simple and air cooled. Subaru, you have more to deal with.

Automobile and aircraft engines are designed for very different duty cycles. A car engine may reach its rated HP output intermittently and briefly during acceleration, or pulling up a long hill. An aircraft engine, OTOH, will run at full power for 5-10 minutes (takeoff and climb), then cruise at 75-80% power for hours. So cooling becomes a huge factor... I'm not familiar with Subaru conversions but cooling is the limiting factor on VW conversions, which is why they top out well under 100HP. RPM is also a factor, auto engines are designed to produce their HP at a much higher rpm than is efficient for a propeller, so you need a redrive or you take the hit on propeller efficiency.

Electronic engine controls are also another factor; in cars they're designed around a the car's duty cycle and optimized for reduced emissions (for example turning on the check engine light if the catalytic converter fails, but you won't have a cat on a plane). They often include a reduced power "limp mode" to get you home if something fails, but in an airplane that reduced power might be just enough to get you to the scene of the crash.

Car engine parts are cheaper-- often a lot cheaper-- but a BJC pointed out above you have to consider the total cost of a failure, when you can't just pull over to the side of the road and fix it, or wait for a tow truck. When I flew my half VW powered plane, I was always looking for a place to land, expecting the engine to quit at any time (it never did, completely).

So what do you have to do or make? As I said, I'm not familiar with the specifics of Subarus in airplanes, but in general, you'll probably need to:
  • Make or buy and install an output pulley for the reduction drive
  • Make or buy an exhaust system to suit the airplane
  • Install a simplified ECU, or convert to carburetor
  • If you remove the stock ECU and go carburetor, install a new ignition system
  • Make and install plugs or covers for removed sensors, etc.
  • Make an engine mount
  • Make or buy a reduction drive-- a biggie, not nearly as simple as it looks, torsional vibration is the bane of redrives, sometimes you get lucky and sometimes you don't without some serious engineering effort.
  • You may have to move (and fabricate brackets for) accessories like the alternator
  • Design and fabricate a new cooling system (radiator, hoses, etc.) to suit the aircraft installation
  • Design and fabricate the cowling and ducting to direct air around the engine, not as simple as just hanging a radiator on the front of a car
If I was looking at auto conversions for the reduced cost, a VW would be the only choice, it's the only one with the established history and knowledge base to know it'll be reliable... but it still won't be as reliable as a Continental or Lycoming, and will require more attention during its lifetime. Any of the others, including Subaru, should be contemplated only if you go into it as an experimental project, and expect to (and enjoy!) spend a lot of extra time working on it both during the build and on an ongoing basis after it's flying, working out how to solve problems (there's a big difference between mechanicing an existing design and engineering something something new). Not to say that you shouldn't do it, but do it for the right reasons and know what you're getting into.
Thank you for the thoughtful post. I would agree with the VW being the choice, but I'm not going to try and fly a 4 seat plane behind a100hp or less engine. I'm looking for 140hp, minimum. That is why I'm looking at the Subaru as an option. It is the right hp range by all accounts.
 

mcrae0104

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GS- just go fly. Don't worry about the Sling or the right engine for right now. Your opinions will evolve after you're flying, and if they stay the same you haven't lost anything.
 

BBerson

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Dick Vangrunsven learned much and tested his design skills first with a one seater. Can't kill a passenger if one seat. Think about the responsibility involved as pilot in command when with a passenger that trusts the pilot and with no knowledge of risks.
I don't think Van ever considered an auto engine.
 

blane.c

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Dick Vangrunsven learned much and tested his design skills first with a one seater. Can't kill a passenger if one seat. Think about the responsibility involved as pilot in command when with a passenger that trusts the pilot and with no knowledge of risks.
I don't think Van ever considered an auto engine.
I used to take up my friends in my experimental cubby. They would see the big experimental sign and ask "what's experimental about it" and I'd reply "everthing".
 

blane.c

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I doubt you had anything truly experimental like a PSRU in your Cubby.
Engine was O-290-D2 with a 82" McCauley Borer prop 42" pitch. Twice the fuel capacity as standard Super Cub 72gallons but no header tank. Atlee Dodge brace in skylight area. Atlee Dodge heavy duty gear and 30" floatation tires with air stem in sidewall (were it belongs on a bush plane) and disc brakes. 900lbs empty. PA-11 fuselage (top deck cut out and Super Cub top deck welded in) 1st year no flap Super Cub wings with 14 inch long spoilers added (so you could get rid of excess lift when necessary). Atlee Dodge cross brace in empennage, extended baggage and custom door access. Skiis in winter. PA-11 horizontal stabilizer (a lot less surface than a Super Cub) so the tail dropped 1st, like dragging a hook. And stuff.
 

TFF

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That is not do much experimental as picking the best bits of a certified line of planes. Even using certified stc stuff.
 
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